Electric clock



y 1945. J. FINK ET AL 2,374,987

ELECTRIC CLOCK Original Filed Nov. 12, 1940 NVENTORS: 17a an fin Z BY T/zomas B-Gz'bbs Patented May 1, 1945 ELECTRIC CLOCK Jean Flnkand Thomas I. Gibbs, new... WIL,

asslgnors to George W. Borg Corporation, Chlcago, Ill., a corporation of Delaware Original application November 12, 1940, Serial No. 365,240, now Patent No. 2,358,983, dated August 29, 1944. Divided and this application October 29, 1942, Serial No. 463,834

1 Claim.

The present invention relates in general to electric clocks, and more in particular to clocks of the type in which the mainspring is omitted and an electromagnet is employed to maintain the balance in oscillating condition, the magnet being intermittently energized under control of the balance. Clocks of this type are well adapted for use in automobiles, and the object of the invention may therefore be considered to be the provision of a new and improved automobile clock, although the invention is not necessarily so limited and may be used in other types of clocks.

A feature of the invention is a new and improved drive mechanism by means of which the oscillatory motion of the balance is converted into a unidirectional motion of the clock train with a minimum of interference with the free motion of the balance.

This application is a division of an application for improvements in Electric clocks, Ser. No. 365,- 240, filed November 12, 1940, now Patent No. 2,356,983 granted Aug. 29, 1944.

The invention will be described in detail hereinafter, reference being had to the accompanying drawing, in which- Fig. 1 is a rear view of a clock constructed in accordance with the invention;

Fig. 2 is another rear view of the clock, on a larger scale, and with the back frame plate removed;

Fig. 3 is a side view looking toward the balance as seen in Fig. 2;

Fig. 4 is another side view taken from the left as the clock is seen in Fig, 3;

Fig. 5 is a fragmentary View showing details of the contact device for controlling the circuit of the electromagnet;

Fig. 6 is a perspective view of the electromagnet spool and terminals before winding;

Figs. 7, 8, 9 and 10 are diagrammatic views showing the essential parts of the drive mechanism in the different positions which they assume during the oscillation of the balance; and

Fig. 11 is a fragmentary sectional view takenon the line I I in Fig. 2.

Referring to the drawing, the various parts of the clock are mounted on a frame which comprises the front plate 2, the plate 3, and the three posts 5, 5 and I. The front plate 2 may be circular in shape and has the three posts secured to it by a riveting or staking operation, as indicated in Figs. 3 and 4 of the drawing. Each post is reduced in diameter for about half its length, as shown by the dotted lines, and the ends of these reduced portions are threaded. The

shape of the plate 3 can be seen from Fig. 2. which indicates that in the vicinity of posts I and 6 the outline of the plate conforms to the inner surfaces of the pole pieces I9 and II, except for the two ears -8 and 9, which pass through slots in the pole pieces and are drilled to receive the reduced portions of the posts. Plate 3 is also drilled at a point corresponding to the location of the post I.

The two pole pieces I0 and II are forced on to the ears 8 and 9, respectively, of the frame plate 3 before the latter is assembled and are retained by the press fit. The plate 3 may then be placed in position against the shoulders on posts 5, 6 and I, after which the tubular spacers I2 and I4 are assembled on posts 6 and 1, respectively, and a short square spacer I3 on post 5. One side of the spacer I3 fits closely against the outer surface of the pole piece I I. The spring unit l5 may then be placed in position on post 5, above the square spacer I3. This spring unit comprises a spring I6 for controlling the pallet lever and. a contact spring I! for controlling the magnet circuit, formed integrally with one another. The common portion of the spring unit is provided with three ears l8 which preferably grip the sides of the spacer I3 tightly when the spring unit is placed in position, the latter being forced down until it rests on top of the spacer. A short spacer I9 is now added, whereupon the assembly may be firmly secured together by means of nuts 20, 2| and 22. It will be understood that other parts of the clock may have to be placed in position before the plate 3 is assembled.

The described construction involving the square spacer I3 cooperating with the pole piece II and the ears I8 on spring unit I5 is of considerable advantage in that it enables the nut 2| to be tightened up without any special precaution being taken against rotating the spring unit on post 5. This spring unit is automatically positioned when it is assembled and its position cannot be disturbed when the nut 2| is drawn down.

The back plate 4 may be regarded as part of the frame, althoughit is readily removable. It has holes drilled to correspond to the locations of posts 5, 6 and I, and is clamped in position aggianst the nuts 29, 2| and 22, by three nuts such as The balance comprises a ring 50, of brass or other suitable material, and a four pole armature which also functions as a support for the ring. The armature is a sheet metal stamping of high grade magnetic material and is shaped as shown in Figs.'2, 3 and 4. The four pole pieces are indicated at 52, 53 and 54, and are connected to a central hub section by means of spokes formed integrally therewith, as shown. The ends of the poles are bent at right angles on arcs of a circle of the same diameter as the outer.

periphery of the ring 50, thus forming a partial enclosure for the ring, which may be held in position by a press fit, or in any suitable manner.

The balance is mounted on an arbor 25, which has a jeweled bearing at one end in the downturned portion 26 of frame plate 3, as shown in Fig. 2. At the other end the arbor 25 has a plain jeweled bearing and also a thrust bearing, which are supported on the balance cock 21 in known manner. The thrust bearing is required because the clock is intended to be mounted with the balance arbor in a vertical position. The balance cock is provided with a base 28, which is secured to the frame plate 2 by means of screw 29. It will be noted that the bearings for the balance arbor are located so close to the frame plate 2 that the rim of the balance projects slightly beyond the face of the plate, the latter having an opening therein, as shown in Fig. 2, in which the balance oscillates. The purpose of this construction is to enable the oscillating balance to be observed from the front of the clock, it being understood that the dial will be provided with a similar opening.

The usual hairspring is indicated at 30 and has one end secured to the balance arbor and the other end secured to a stud 3| which projects from the base 28 of the balance cock. A regulating mechanism is also provided, as shown, and includes a toothed sector 32 which is rotatably mounted on the balance cock in known manner. The sector 32 is in mesh with a gear 33 which is mounted on the under side of plate 4 and may be rotated by means of a pointer 34. These parts are of the usual construction and require no detailed description. It will sumce to say that rotation of pointer 34 rotates the gear 33 and sector 3'2 and that the latter moves the regulating pins along the hairspring to change the effective length thereof.

Extending parallel to the balance arbor 25 there is an arbor 40, on which is mounted the escape wheel 38, as seen in Figs. 2 and 11. The arbor 40 has a bearing at one end in the post 1, as seen in Fig. 4. At the other end, the arbor 40 has a bearing in the member 4| which forms part of a bracket including the base 42, Fig. 3. The bracket is secured to the frame plate 2 by means of a screw 43. The arbor 40 drives the. clock movement by means of worm 44 and a gear in mesh therewith which is mounted on the shaft 45. The rest of the gear train may be of known construction and has been omitted in order to avoid confusing the drawing.

The escape wheel 38 is rotated by means of a pallet lever 39, the shape of which is seen best in Figs. 7 to 10, inclusive, and the two pallets 4B and 49, which may be hardened steel pins. The pallet lever 39 is supported on a short shaft 41 which has a bearing at one end in the bracket member 4| and at the other end in a raised por tion of the frame plate 3, as shown in Figs. 2 and'll. The spring l6 cooperates with the pallet lever 39 and tends to maintain it in the position in which it is shown in Fig. 7. For actuation of the pallet lever by' the oscillating balance, a pinion 36 is provided on the balance arbor 25, the said pinion having a single tooth 31 adapted to engage the end of the pallet lever.

The electromagnet comprises a core 51, a winding 58, and a spool and terminal assembly which is shown in perspective in Fig. 6. The spool comprises a hollow body portion 60 and the two heads BI and 62, and is preferably molded from some suitable plastic material. The terminal members 63 and 64 are embedded in the heads 6| and 62, respectively, and the terminal member 63 is provided with a soldering lug 66 formed integrally therewith and projecting from the head 6|. The core 5'! is inserted in the spool, which may be reamed out if necessary, and should fit closely therein. After the core has been inserted the winding 58 and its cover are put on in known manner. The terminal members 63 and 64 and lug 66 are then bent back along the winding to the positions in which these parts are shown in Figs. 2 and 5.

The reference numeral 59 indicates a condenser, which has two heavy terminal conductors 10 and H. These terminal conductors are cut off to the proper length and are then formed as shown in Fig. 2. The ends 12 and 13 of the winding 58 are wrapped around conductors Ill and H, respectively, and the latter are then soldered to terminal member 64 and lug 66, respectively, as shown in Fig. 2.

Assuming that the back plate 4 has not yet been assembled, the electromagnet assembly may be placed in its proper position, with the core 51 in the slots of the pole pieces Ill and II and the fiat sides of the spool heads 62 and GI resting on the frame plate 3. The nuts 61 and 68' serve to clamp the pole pieces I0 and II to the core .51, which is preferably provided with shoulders in line with the ends of the spool. It will be seen from the foregoing that the magnet assembly is made as a separate unit, which is incorporated in the clock at a convenient stage in its manufacture, preferably after assembly of the mechanical parts has been completed. This is of considerable advantage for obvious reasons. The described construction also facilitates repairs in case of a defective condenser or magnet wind- The contact device for controlling the electromagnet is best seen in Fig. 5. As previously explained, the spring unit I5 is clamped above the square spacer l3 on the frame post 5 and includes the contact spring l1. This contact spring cooperates with a contact member 65 which is formed integrally with the terminal member 63. Spring [1 is tensioned in an upward direction, as seen in Fig. 5, so that it tends to break contact with the contact member 65. The spring is operated to close the contact by means of an armature 90, secured to the spring, and a small permanent magnet 9|, which is mounted on the balance arbor. The magnet 9| is preferably made of Alnico and has an opening in which there is fitted a bushing 92, which has a press fit on the arbor 25. The poles of the magnet are at. the opposite ends thereof, and the magnet is eccentrically mounted on the arbor so that during the oscillation of the balance one of the poles comes much closer to the armature than the other pole. The distances are so proportioned to the strength of the magnet that the armature can be attracted only by the pole which comes the closest to it.

Fig.5 shows the armature 90 in attracted position, the contact between spring l1 and contact member 65 being closed. When the arbor 25 and not close the contact because the pole at the the arbor will bisect the angle formed by the spokes which support the poles and 52 of the balance armature. This relation can be seen from Fig. 3, which also shows that when the balance is symmetrically located with respect to poles 55 and 55, with pole 55 midway between armature poles 5| and 54, the operative pole of magnet 9| is in alignment with the armature 90.

The circuit connections for the electromagnet 58 may now be described. There is a binding post 81 mounted on the back of frame plate 4, which is provided with a spring clip 88 beneath the frame plate. When the frame plate 4 is in assembled position, the clip 88 presses against the terminal member 54, as seen in Fig. 4. Assuming that the clock is used in an automobile, the ungrounded pole of the storage battery is connected to the binding post 81. The complete circuit for the electromagnet may then be traced from the ungrounded pole of the storage battery by way of the binding post 81, clip 88, terminal 64, conductor l2, winding 58 of the electromagnet, conductor l3, soldering lug 66, terminal member 53, contact member 65, spring I! (armature 90 being in attracted position), and through said spring to the frame of the clock. Since the frame of the clock is grounded on the car, the circuit is completed by way of the chassis of the car to the grounded pole of the battery. This circuit is closed intermittently during oscillation of the balance by means of the magnet 9|, armature 90, and spring H. The condenser 59 is included in the circuit in parallel with the magnet winding 58 and prevents sparking at the contact between spring I! and contact member 65 when the circuit is broken. It will be understood also that these parts are equipped with suitable contact points of non-corrosive metal as indicated in Fig. 5.

The construction of the clock and the various parts thereof having been described, the operation of the clock may be explained briefly.

The hairspring 30 is so assembled and adjusted with respect to the balance that when the battery is disconnected the hairspring will tend to return the balance to the position in which it is shown in Fig. 3. In this position the poles 55 and 56 are midway between the adjacent armature poles on the'balance, and the operative pole of magnet BI is adjacent to armature 90. The adjustment of the hairspring is not at all critical, since the attraction between the magnet 9| and the armature 99 will rotate the balance to the position in which it is shown, provided the hairspring adjustment is approximately correct. In other words,'the magnet 9| will pull itself in, if brought within range of armature 90 by the hairspring, and will maintain the circuit of the electromagnet 58 closed inside the clock at the contact spring I1.

When the battery is connected, a flow of current over the previously tracedcircuit is established and the electromagnet 58 is energized. The resulting magnetic field passes through the armature and the balance is thus placed in a condition of unstable equilibrium. The rotative forces tending to rotate the balance in opposite directions will not be exactly equal, for various reasons, and the balance will start to rotate in one direction or the other. It may be remarked at this point that when the balance is in the position of Fig. 3 the tooth 31 on pinion 38 is in engagement with the pallet lever 39 on one side or the other thereof and consequently the tension in spring I5 will insure a slightly unsymmetrical location of the balance armature with respect to the poles 55 and 58. I

As soon as rotation of the balance begins, the torque rapidly increases. for one pair of armature poles will be approaching the magnet poles while the other pair is receding therefrom. Thus the balance is given a substantial rotative impulse before the magnet 9! has traveled for enough to release armature and break the circuit. The rotation of the balance tensions the hairspring 30 and the direction of rotation is shortly reversed, with the result that the circuit of the elecromagnet is again closed when the magnet 9| comes within operating distance of the armature 80. Thus the balance is given another rotative impulse, but in the opposite direction. The operation continues in this manner and in a very short time the balance will attain its normal amplitude, a power impulse being received during each oscillation or beat, when the operative pole of magnet 9| passes the armature 90.

In further explanation it may be pointed out that notwithstanding the symmetrical arrange-.

ment of the magnet and armature poles and the magnet 9|, the closure of the circuit by the magnet during each beat produces effective rotative impulses applied to the balance-which initiate and sustain the oscillations as stated. This is due to the fact that the building up and collapse of the magnetic field is delayed by several factors, including the capacity of the condenser 59 and the inductance of the magnet winding 58, whereby the successive energizations of the electromagnet are caused to occur at times when the balance armature is in such positions with respect to the magnet poles that the impulses received are preponderantly effective in the direction in which the balance is moving. In other words, the delay in the establishment and decay of the magnetic field causes the major portion of the flux to be established each time after the balance has passed dead center and when one pair of poles is approaching and entering between the magnet poles.

The oscillation of the balance drives the clock movement through the medium of the pallet lever 39 and the escape wheel 38, the latter being fixed to the arbor 40 carrying the worm 44, which is the first element of the gear train. The manner in which the drive mechanism operates can best be explained in connection with Figs. 7 to 10, inclusive, which show the essential parts on an enlarged scale and with the several views unobstructed by other parts. The figures show the parts as viewed from the left in Fig. 3.

The normal position of the pallet lever 39 is as shown in Fig. 7 or Fig. 9. The position of the pallet lever is the same in these figures, but the relation between the pallets and the teeth of the escape wheel is diiferent, as will be presently explained. Figs. 8 and 10 show the pallet lever fully actuated in its two directions of movement, respectively. When the clock is not running the tooth 31 of pinion 36 will be in engagement with the end of the pallet lever 39 on one side or the other, depending on chance, for the hairspring 30 and magnet 9i tend to bring the balance in such a position that the radius of tooth 31 is in alignment with the pallet lever, as has already been mentioned. When the clock is running, however, the pinion tooth 31 is out of engagement with the pallet lever at all times except when the balance is passing through its mid position. This insures that the motion of the balance is free and unimpeded except for very brief periods, which corresponds approximately to the periods during which power impulses are supplied to the balance. 1

Considering Fig. 7 now, it is assumed that the j balance arbor 25 and pinion 36 are rotating in the direction shown by the arrow. When'the tooth the palletlever reaches the extreme position shown in Fig. 8, when the tooth 31 slips off the end of the pallet lever and the latter is instantly restored by spring it to the position in which it is shown in Fig. 9. Examination of Figs. 8 and 9 will show that the escape wheel has been advanced by the described operation of the pallet lever, and it will be seen from Fig. 9 that the pallet 49 is now behind tooth 83 instead of in front of it as in Fig. '7. It will be noted also that both pallets 48 and 49 are within the circle defined by the extremities of the teeth of the escape wheel and that pallet 48 in particular is just in front of tooth 82 where it can'prevent any tendency of the escape wheel to overrun.

After the pinion tooth 3! has released the pallet lever, the pinion and arbor 25 continue to rotate in the direction of the arrow in Fig. 8 until the balance stops and reverses its direction of motion under the influence of the hairspring. Rotating now in the direction shown by the arrow in Fig. 9, the pinion tooth 31 again approaches the end of the pallet lever and eventually engages it as before, but on the opposite side. The pallet lever and shaft 41 are therefore now rotated in a counter clockwise direction. As the result of this movement the pallet or pin 48 is lifted from in front of tooth 32 of the escape wheel and the wheel is advanced by the engagement of the pallet 49 with tooth 93. The rotation of the pallet lever continues until it reaches the extreme position shown in Fig. 10, which shows the parts in the positions they occupy just before the pinion tooth 31 slips oil the end of the pallet lever.

When this occurs the pallet lever is restored by spring l6 as before and assumes the position in which it is shown in Fig. 7. Consideration of Fig. 10, however, will show that the pallet 49 is now just in front of tooth 84 instead of tooth 83, and that the escape wheel has been advanced on angular distance of one full tooth. The escape wheel- 38 is again locked against overrun. this time by pallet 49 cooperating with tooth 84.

.The foregoing describes one complete cycle 0! operation, during which the balance wheel performs an oscillation or beat in each direction. The cycle repeats itself indefinitely as long as the clock continues to run and the escape wheel is thus intermittently advanced always in the same direction to drive the clock train in the proper manner.

The invention having been described, that which is believed to be new and for which the protection of Letters Patent is desired will be pointed out in the appended claim.

We claim:

In a clock, a drive mechanism for converting the oscillating motion of the. balance to a unidirectional motion of the clock train, said mechanism comprising a toothed wheel for driving said train, a lever having pallets for advancing said wheel, said lever comprising two pallet arms extending substantially at right angles to each other, a pivot for said lever at the junction of said arms, a flat spring normally bearing on said lever at two points located on opposite sides of said pivot, and means for intermittently engaging one of said arms to oscillate said lever responsive to oscillation of the balance.

JEAN FINK.

THOMAS B. GIBBS. 

